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**Constraining supersymmetric models. Using Higgs physics, precision observables and direct searches.**
*(English)*
Zbl 1331.81010

Springer Theses. Cham: Springer; Hamburg: Univ. Hamburg (Diss.) (ISBN 978-3-319-22227-1/hbk; 978-3-319-22228-8/ebook). xvi, 205 p. (2016).

Publisher’s description: This thesis analyses how supersymmetric (SUSY) extensions of the standard model (SM) of particle physics can be constrained using information from Higgs physics, electroweak precision observables and direct searches for new particles. Direct searches for SUSY particles at the LHC have not resulted in any signal so far, and limits on the SUSY parameter space have been set. Measurements of the properties of the observed Higgs boson at 125 GeV as well as of the W boson mass can provide valuable indirect constraints, supplementing the ones from direct searches. Precise calculations are performed for Higgs decays and electroweak precision observables within the minimal supersymmetric extension of the standard model and the next to-minimal supersymmetric extension of the standard model. Furthermore, a method is presented to reinterpret the LHC limits from direct SUSY searches in more realistic SUSY scenarios. The phenomenological consequences of those results are thoroughly analysed.

From the summary: We present various complementary possibilities to exploit experimental measurements in order to test and constrain supersymmetric (SUSY) models.

This thesis is divided into three major parts: In the first part we present the currently most precise prediction for \(M_W\) in the Minimal Supersymmetric Standard Model (MSSM) with complex parameters and in the Next-to-Minimal Supersymmetric Standard Model (NMSSM). The evaluation includes the full one-loop result and all relevant available higher-order corrections of Standard Model (SM) and SUSY type.

In the second part of the thesis we discuss possible interpretations of the observed Higgs signal in SUSY models. The properties of the observed Higgs boson are compatible with the SM so far, but many other interpretations are also possible.

In the third part of this thesis we present a tool, called Fastlim, to calculate conservative limits on SUSY models from direct SUSY searches at the LHC. Experimentalists present their results from direct SUSY searches in simplified scenarios of more general models. The impact of their results on many other SUSY scenarios has not been investigated, so that the impact of the existing search limits on realistic SUSY scenarios is difficult to assess. Using Fastlim, the results can be reinterpreted in other (less-restricted) models without performing any Monte Carlo event generation. The program reconstructs the visible cross section from pre-calculated efficiency and cross section tables for simplified event topologies. As an application of our tool, we study the constraints from direct LHC searches on the parameter space of “natural” SUSY models.

From the summary: We present various complementary possibilities to exploit experimental measurements in order to test and constrain supersymmetric (SUSY) models.

This thesis is divided into three major parts: In the first part we present the currently most precise prediction for \(M_W\) in the Minimal Supersymmetric Standard Model (MSSM) with complex parameters and in the Next-to-Minimal Supersymmetric Standard Model (NMSSM). The evaluation includes the full one-loop result and all relevant available higher-order corrections of Standard Model (SM) and SUSY type.

In the second part of the thesis we discuss possible interpretations of the observed Higgs signal in SUSY models. The properties of the observed Higgs boson are compatible with the SM so far, but many other interpretations are also possible.

In the third part of this thesis we present a tool, called Fastlim, to calculate conservative limits on SUSY models from direct SUSY searches at the LHC. Experimentalists present their results from direct SUSY searches in simplified scenarios of more general models. The impact of their results on many other SUSY scenarios has not been investigated, so that the impact of the existing search limits on realistic SUSY scenarios is difficult to assess. Using Fastlim, the results can be reinterpreted in other (less-restricted) models without performing any Monte Carlo event generation. The program reconstructs the visible cross section from pre-calculated efficiency and cross section tables for simplified event topologies. As an application of our tool, we study the constraints from direct LHC searches on the parameter space of “natural” SUSY models.

### MSC:

81-02 | Research exposition (monographs, survey articles) pertaining to quantum theory |

81V22 | Unified quantum theories |

81T60 | Supersymmetric field theories in quantum mechanics |